\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=latex,scale=1.2]
  % \useasboundingbox(-1,-2)rectangle(8,6);
  \draw[->](0,0)--++(45:1.0);
  \fill[inner color=white,outer color=red!50](0,0)circle(0.2)node{\scriptsize$+$};
  \fill[inner color=white,outer color=blue!50](125:0.17)circle(0.04)node[above]{$-e$};
  \draw[->](-0.5,1.8)--++(-30:1.0);
  \fill[inner color=white,outer color=blue!50](-0.5,1.8)circle(0.04)node[above]{$-e$};
\end{tikzpicture}
\end{document}